D. Edwards; Feehan, J. (1980). “Records of Cooksonia-type sporangia from late Wenlock strata in Ireland”. Nature. 287 (5777): 41–42. doi:10.1038/287041a0.
pryerlab.net
Smith Alan R., Kathleen M. Pryer, E. Schuettpelz, P. Korall, H. Schneider, & Paul G. Wolf. (2006). "A classification for extant ferns". Taxon 55(3): 705-731.